Combination light source with integral voltage converting means



March 8, 1960 E. DAWl-EY 2,928,024

COMBINATION LIGHT SOURCE WITH INTEGRAL VOLTAGE CONVERTING MEANS FiledJuly 16, 1956 II n INVENTOR. 6. E: DHWZE'Y.

COMBINATION LIGHT SOURCE WITH INTEGRAL I VOLTAGE CONVERTING MEANSClarence E. Dawley, Bloomfield, N.J., assignor to West-- 2,928,024Patented Mar. 8, 1960 operationof the lamp on an alternating powersource would produce only half wave cathode-excitation of the phosphorat full line voltage or full wave excitation thereof at half the linevoltage applied to the filament. In

either case, a proportionate decrease in the light generated by thephosphor and the total light output thus inghouse Electric Corporation,East Pittsburgh, Pa.,

a corporation of Pennsylvania Application July 16, 1956, Serial No.598,089

' 6 Claims. 01. 315-51 This invention relates to electric lamps, andmore particularly, to lamps in which the visible radiations generated byincandescent and cathodoluminescent materials are combined toefiiciently produce light of the desired intensity and color.

Lamps of the character mentioned may be termed combination light sourcesand generally consist of an ordinary tungsten filament or other suitableincandescible element having high luminous-efiiciency and highelectron-emissivity supported and sealed within an evacuated envelope inaccordance with standard incandescent lampmanufacturing practice. Inplace of the so called inside frost or light diffusing coatingcustomarily utilized in regular incandescent type lamps marketed forgeneral household use, however, the inner surface of the envelopecarries a high-temperature phosphor that generates light of apredetermined wave length or color under the impact of electrons whichphenomenon and method of phosphor excitation are generally referred toin the art as cathodoluminescence and cathodo-excitation re-.spectively.

If the phosphor is electrically-conductive and lighttransmissive it isapplied directly to the glass surface; otherwise, it is intermixed withor deposited on a layer of material having these attributes. The coatingis connected to either themidpoint or one end of the filament producedwould result thereby materially decreasing the efiiciency of the lamp.The alternative arrangement employing an external'D.C. power source anda three-light thereby applying a steady or pulsating positive potentialto the coating when the filament is operated from and AC. power sourceand establishing an electrostatic field which impels the electronsemitted by the filament toward the phosphor layer. The ensuing electronbombardment and cathodo-excitation of the phosphor cause it to luminesceand emit light energy of such character that the luminosity of the lightgenerated by the filament is intensified and the color thereof enhancedthrough the addition of visibleenergy in that portion of the spectrum inwhich light from the filament is deficient. In the alternative, anexternal DC. power source and a so called three-light lamp base may beemployed to maintain the phosphor coating at a fixed positive potentialwith respect to the filament and effect the desired cathodoexcitation ofthe phosphor.

Combination light sources of the character abovedescribed are disclosedand claimed in copending application, Serial No. 380,408, filedSeptember 16, 1953, now U.S.-Patent No. 2,759,119 assigned to theinstant assignee. However, light sources of this character in order tobecome economically and commercially feasible must be operative atordinary line voltages of alternating current from conventional typesockets and circuits now in use. This requirement has presented aserious obstacle to the development of a practical lamp of this typeinasmuch as lamps constructed and operated in accordance with the abovementioned patent inherently do not utilize to the greatest degreepossible the light-generating capabilities of the phosphor since thefilament and phosphor coating are electrically coupled in such a mannerthat base to maintain the desired degree and constancy of' electricalpotential between the filament and the phosphor corrects the foregoingdeficiency but has also been found to be impractical from a commercialstandpoint due to the expense and inconvenience involved.

It is accordingly the general object of the present invention toovercome and avoid the foregoing deficiencies a and objections to theprior art construction and operation of'combination light sources byproviding a lamp of this character which will operate at optimumefiiciency from conventional type sockets and alternating current powersupply outlets now in use.

A more specific object of the invention is to provide means for simplyand efiiciently increasing the cathodeluminescence of the phosphoremployed in a combination light source.

Another object of the invention is to provide anincandescent-cathodoluminescent lamp of simple rugged constructionhaving built-in means for maintaining the phospher continuously positiveand at substantially full line voltage with respect to the incandescentelectrona potential, with respect to the filament, substantially equalto the voltage applied to the filament from the line.

A better understanding of the invention may be obtained by referring tothe accompanying drawing in which like numerals of reference indicatesimilar parts throughout the'several views, wherein:

Fig. 1 is an elevational view of an incandescentcathodoluminescent lamp,partly broken away and in section, which has been modified to includethe invention; 7

' Fig. 2 is a cross-sectional view through the basal end portion of thelamp along the line II-II of Fig. 1, in the direction of the arrows,showing the manner in which the voltage converting means of the presentinvention are integrally combined with the base member;

Fig. 3 is a perspective view on an enlarged scale of the sealed-in endportion of the lamp shown in Fig. 1 at one phase in its fabricationaccording to the preferred form of the present invention and illustratesthe relationship and disposition of the rectifyingelements and leadinconductors just prior to their introduction into the ase;

Fig. 4 is a view similar to that shown in Fig. 3 but illustrates analternative embodiment of the present invention wherein the rectifiersare mounted within the en- "ous lamp components according to the presentinvention.

Although the principles of this invention are broadly applicable toother types of combination light sources in addltion to those disclosedand described in the aforementioned patent, the invention is especiallyadapted for use with incandescent-cathodoluminescent lamps whichReferring now to the drawing in detail, Fig. 1 illus-' trates oneembodiment of the present invention wherein a combination incandescentand cathodoluminescent light source having a conventional screw typebase member is provided with the integral voltage converting means ofthe present invention. of an envelope 12 having an enlarged sphericalshaped portion and a restricted cylindrical neck portion which is fusedto a re-entrant stem 34 and shaped while plastic to provide a moldedseal 42. A base member comprising a threaded cylindrical metal shell 14and an insulating button 16 carrying an end contact 18 is fitted overthe sealed-in end portion of the envelope 12 and cemented or otherwisefastened thereto to facilitate connection of the lamp with a source ofelectrical energy through conventional type sockets customarily employedin general lighting fixtures. The interiorly disposed end portion of thestem 34 is sealed off and worked while plastic to form a T-shaped press36 through which a pair of main con- 7 ductors 26, 28 and an auxiliaryconductor 27 are hermetically sealed in triangular spaced relation. Themain conductors 26, 28 project upwardly into the spherical shapedportion of the envelope 12 Whereas the auxiliary conductor 27 extendsonly a short distance from the press 36.

A coaxially disposed glass arbor 32 the inner end of which is enlargedto form a button 30 may be interposed between the main conductors 26, 28and fuse-d to the press 36 to provide means for buttressing thestructure. A linear coiled-coil tungsten filament 22 or otherincandescible element having high luminous-efiiciency andthermal-emissivity is transversely mounted onthe inner end portions ofthe main conductors 26, 28 and an axial support 24 and laterallyextending tie wires 23 of molybdenum or other refractory material havinga high melting point are desirably embedded in the arbor button 3tll andcoupled to intermediate portions of the filament 22 and main conductors26, 28, respectively, to keep the desired degree of tension on the coiland strengthen the filament mount assembly in the manner shown anddescribed in US. Patent No. 2,145,911 issued February 7, 193 9, to W. E.Anderson et al.

The interior wall portion of the envelope 12 carries alight-transmitting electrically-conductive high-temperature phosphor,such as manganese-activated zinc fluoride or other suitable materialwhich will luminesce under the bombarding influence of low voltageelectrons; or, in the alternative, a light-transmitting conductivecoating such as a glass or glaze containing tin oxide may be depositedon the bulb wall and a phosphor layer formed thereon to form a compositecoating or the phosphor may be admixed with conductive material, if notnaturally conductive, as described in US. Patent No. 2,759,119previously referred to. The phosphor-including coating 20 may beconveniently connected to the interiorly disposed end portion of theauxiliary conductor 27 by means of a resilient arcuate extension 40,rigidly fastened to said conductor, as by welding, and of suchconfiguration that it is compressed during the fabrication of the lampinto firm contacting engagement with the restricted neck portion of theenvelope 12 and the conductive coating 20 thereon in the mannerdisclosed in the above-mentioned patent. V

The essence of this invention resides in the provision of means forconverting an alternating voltage applied to the main lead-in conductorsand filament to a unidirectional electrical potential impressed acrossthefilament and phosphor deposited on the envelope and in the manner inwhich the converting means is integrally combined with and connected tothe lamp to increase its operating efficiency and these arehereinaftermore fully described.

As will be seen in the preferred form of the invention The lamp consistsgenerally shown in Fig. 1, electrical components 46, 48 of extreme lysmall physical size capable of converting or rectifying AC. voltage toD.C., such as low-current high-voltage type transistors or crystaldiodes, are connected to the outer end portions of the main conductors26, 28 and auxiliary conductor 27 and disposed to lie adjacent thesealed-in end portion of the envelope 12 so that they are completelyenclosed and protected by the base member attached thereto. Inasmuch asthe electrical characteristics of such elements are generallydeleteriously affected by excessively high ambient temperatures, a heatdeflecting disc 33 of reflective material, such as aluminum, providedwith suitably disposed apertures and a radial slot 39 (see Fig. 3) maybe threaded over the main con- .ductors 26, 23, auxiliary conductor 27and its contacting extension 40, and arbor 32 during fabrication of thefilament mount assembly and firmly seated on the stem press 36transverse to the lamp axis and locked thereat by the divergent endportions of the conductors 26, 28 to shield the basal end portion ofthe'lamp from the incandescent filament and reduce to a minimum theambient temperature within the base during the operation of the lamp. Ifthe shield material is conductive due care should be exercised toinsulate it from at least one of the main conductors 26, 28 as bygrommets of nonconductive material inserted into the apertures intendedto receive the conductors, in order to obviate the danger of a shortingout the filament 22 and causing a destructive arc.

The number of free electrons liberated from the tungsten filament of anordinary 60 or 100 watt incandescent lamp by thermal emission duringnormal operation is sufliciently high that current densities in theorder of 250 to 500 ma. can reasonably be expected as a result of theelectron flow from the filament 22 to the phosphor-in eluding coating26. Of course, the number of electrons emitted by the filament 22 may beincreased and the the, intensity of the resultant cathodo-excitation ofthe phosphor thereat proportionately increased by adding a low workfunction material, such as thorium, to the tungsten from which thefilament 22 is made to provide a thoriated tungsten filament, as is wellknown in the art.

Since each of the rectifying elements 46,48 are in series with thecoating 20 on alternate half cycles of the applied voltage during A.C.operation, as will be herein after more fully described, they must havesufficient current carrying capacity to handle the electron flow duringthis period. Furthermore, the elements 46, 48 must be able to withstandthe voltage applied to the filament 22 with neglible leakage atrelatively high ambient temperatures, and be of such physical size andconfiguration that they can be readily mounted within the base member orneck of the lamp envelope 12. Rectifying elements having the foregoingphysical and electrical characteristics are marketed by the assigneeunder the trade designation XP-SOSZ rectifying cells. They are fusedjunction type silicon diodes and are available with peak inverse voltageratings from 50 to 600 volts. For domestic A.C. circuits diode XP5052-Dhaving a peak inverse voltage rating of 200 volts would be adequatewhereas for higher line voltages a diode having a higher rating, such asXP5052K with a maximum allowable peak inverse voltage of 500 volts, maybe employed. The cells, as illustrated Figs. 1, 2, 3 and 4, havecylindrical cartridge type cases provided with coaxial stud-liketerminals and have an overall length of /8 inch and an outside diam- 1eter of inch. The maximum instantaneous. leakage current at rated peakinverse voltage and a temperature of 150 C. is 0.5 ma..and themaximumallowable DC. output current ranges from 250 ma. at 150 C.ambient to 500 ma. at C. ambient sothat suflicient current carryingcapacity and breakdown protection are provided thereby insuring reliableoperation throughout the life of the lamp.

parallel guide panels 44 of electrically nonconductive material, such asmica or thelike, through which the terminals of said elements protrudefor electrical connection. The panels 44 are disposed to straddle thelamp axis and are held against the lip of the molded seal 42 by theauxiliary conductor 27 and main conductors 26, 28 which emerge from thestem tube 34 and are bowed to pass outwardly along the sides of thepanels 44 to the terminals of the elements 46, 48 with which they areelectrically connected, as by soldering or other suitable means. Thepanels 44 may be tapered inwardly and the ends of the conductors26, 28bentdownwardly into coaxial alignment and upwardly at an agle,respectively, as shown in Fig.. 3, so that the entire assembly may beconveniently inserted 'into and receive by the base. The foregoingconstruction not only provides an exceedingly simple and ruggedstructure and facilitates assembly of the lamp but also serves toelectrically isolate the various components from each other therebysafeguarding against short-circuits or. arcs which might otherwisepossibly occur should the lamp be subjected to rough handling and severemechanical impacts.

As' shown in Fig. 5, the cathodes of the rectifying elements 46, 48 aretied together and connected by means of the auxiliary conductor 27 andcontacting extension 40 to the phosphor-including coating 20 depositedon the inner surface of the envelope 12. The anodes or positiveterminals of the rectifiers are joined to the main condoctors 26 and 28which in turn are connected to the filament 22 and base member. In thismanner the coating 20 is always at a positive potential with respect tothe filament 22 and the difference in potential is at all timessubstantially equal to the A.C. voltage applied to the main conductors26, 28 from the supply line. Hence, electrons thermally emitted from thefilament 22 during operation of the lamp are attracted toward thecoating 20 and accelerated to a greater degree than was heretoforepossible by virtue of the intensification of the electrostatic fieldtherebetween effected by the increase in potential. The energy level ofthe electrons is thus increased causing them to strike the phosphor withgreater force thereby effecting an attendant proportionate increase inthe cathodoexcitation thereof and overall light output and efficiency ofthe lamp.

'After striking the coating 20 the electrons flow toward the neckportion of the envelope 12, through the contacting extension 40, theauxiliary conductor 27 and through either rectifier 46 or 48 to the mainconductor 7 26 or 28, whichever happens to be positive at theirparticular instant of time, thus completing the circuit. The rectifyingelements 46, 48 are so disposed electrically with respect to thefilamentand main conductors 26, 28 and power line connected thereto thatfull wave rectification of the A.C. voltage is achieved. Thus,substantially the full line voltage appears across the filament 22 andcoating 20 withthe latter always being maintained positiye, except whenthe voltage drops to zero between each half cycle. The elements 46, 48,in a manner of speaking, function'as'a virtual'electronic switch whichoperates in timed sequence and is synchronized with the periodicvoltage'fluctuations of the power supply to constantly keep the coating20 connected to the positive side of the line.

The potential difference between the coating 20 and the filament 22 isthus increased by a factor of two over the prior art arrangement wherebythe coating 20 was connected to the mid-point of the filament 22, or, incontrast to the alternative prior art construction where the coating 20was connected to one side of the filament 22, the full line voltage isapplied twice as long. In either case, since the luminous output of aphosphor is'roughly, proportional to the length of time and intensity ofexcitation, it is obvious that the construction and operation of anincandescent-cathodoluminescent lamp in accordance with the above-statedprinciples of the invention will approximately double the luminousoutput of the phosphor and effect a substantial increase in the overalllight output and efiiciency of the lamp and improve the color of thelight generated thereby. In addition, and of equal significance from apractical standpoint, the improvement is achieved by a relatively simplebut most effective means which is integrally combined with the lamp.

In Fig. 4 there is shown an alternative embodiment of'the inventionwherein a regular incandescent lamp mount comprising a stem tube 34awith a conventional.

flat stem press 36a having two main conductors 26a, 28a hermeticallysealed therethrough and a glass arbor 32a interposed therebetween issealed to the neck portion of the envelope 12a in the usual manner. Inthis embodiment a pair of auxiliary leads 50' are secured to the mainconductors 26a, 28a adjacent the stem press 36a and formed to providelaterally extending arms the end portions of which are bent downwardly,as viewed in Fig. 4, at substantially right angles toward the moldedseal 42a which joins the flared stem tube 34a with the neck of theenvelope 12a. The anodes of the rectifying elements 46a, 48a arefastened to the downwardly projecting end portions of the auxiliaryleads 50 and the negative terminals tied together by a laterallyextending conductive member 52 which carries a resilient contactingextension 40a thereby providing an arrangement which is electricallyequivalent to that employed in the preferred embodiment previouslydescribed. A heat deflector disc 38a is desirably positioned on the stempress 36a in a manner similar to that described previously in connectionwith preferred embodiment so that the rectifying elements 46a, 48a areshielded from the intense heat generated by the filament. This typeconstruction will be advantageous where it is desirable to base andfinally assemble the lamp in the regular manner.

As will be obvious, other types of construction and voltage convertingmeans may be employed, the only limitations being that they must be-ofsuch physical size that they can be integrally combined with the lampand have the necessary electrical characteristic to permit the lamp tobe operated from conventional sockets and standard A.C. power sources.

It will be recognized from the foregoing that the objects of theinvention have been achieved by providing anincandescent-cathodoluminescent lamp with integral voltage convertingmeans which not only increase the cathodo-excitation of the phosphor andresultant luminous output of the lamp and improve its color quality, butpermit the lamp to be operated with optimum efficiency from standardtype sockets and A.C. circuits now in use.

Although the best known mode of carrying out the invention has beenshown and described in accordance with the patent statutes, it will beunderstood that other modifications may be made without departing fromthe spirit and scope of the appended claims.

I claim:

1. An incandescent-cathodoluminescent lamp comprising an envelope havinga neck portion, an inwardly extending stem fused to said neck portion,conductors sealed through said stem and projecting into said envelope,an incandescible filament of thermionic material attached to thesealed-in portions of said conductors and held in spaced apart relationwith said envelope, a light-transmitting electrically-conductivephosphor coating carried by the inner surface of said enveloperesponsive to the electrons thermally emitted by said filament andhaving an efiicient light output in a selective region of the spectrumat the normal operating temperatures of said envelope under low-voltageelectron bombardment, a heat deflecting disc carried by said stem andcoextensive with said neck portion to provide a shielded end chamberwithin said envelope, and rectifying elements secured to the sealed-inportions of said conductors and disposed within the shielded end chamberin said envelope, said elements having their cathodes joined togetherand connected to said coating and their anodes connected to saidconductors so that said coating is maintained continuously positive inpolarity with respect to said filament at a potential substantiallyequal to the voltage applied to the filament when said lamp is operatedfrom an alternating current power source.

2. An incandescent-cathodoluminescent lamp comprising an envelope havinga neck portion, a re-entrant stem fused to said neck portion, anauxiliary and two main conductors sealed through said stem andprojecting into said envelope, a coiled tungsten filament transverselyattached to the sealed-in portions of said main conductors and held inspaced apart relation with said envelope, a light-transmitting coatingon the inner surface of said envelope comprising a phosphor-includingelectrically-conductive material responsive to the electrons thermallyemitted by said filament and having an efficient light output in aselective region of the spectrum at the normal operating temperatures ofsaid envelope under low-voltage electron bombardment, a hollow basemember secured to and enclosing the end of said neck portion andconnected to said main conductors, a heat deflecting disc carried bysaid stem and coextensive with said neck portion to shield said basemember and adjacent section of the neck portion from the filament, meansinteriorly connecting said auxiliary conductor with said coating, and apair of silicon diode rectifiers mounted within said base memberconnecting said auxiliary conductor with each of the said mainconductors, said diodes having their cathodes joined together andconnected to said auxiliary conductor so that said coating is maintainedcontinuously positive in polarity ,with respect to said filament at apotential substantially equal to the voltage applied to the filamentwhen said lamp is operated from an alternating current power source.

3. In combination with an incandescent-cathodoluminescent lamp having anenvelope with a sealed-in portion from which two main conductors and anauxiliary conductor protrude into a hollow base secured to and enclosingsaid sealed-in portion, a plurality of voltage converting elementselectrically arranged and connected to effect full-wave rectification ofan alternating po tential, and means for mounting said voltageconverting elements within said base comprising two panels of insulatingmaterial axially disposed in said base and held in spaced apart relationtherein proximate the sealed-in portion of said envelope by said mainand auxiliary conductors said voltage converting element being locatedbetween and supported by said panels and electrically connected to saidmain and auxiliary conductors.

4. The combination which comprises, means for converting an alternatingvoltage to a unidirectional potential; and anincandescent-cathodoluminescent lamp comprising an incandescible sourceof radiant energy and electrons, a sealed radiation-transmittingenvelope enclosing said source, and a radiation-transmittingelectrically-conductive coating on the inner surface of said envelopecomprising a cathodoluminescent phosphor having an efficient output in apredetermined region of the spectrum at the normal operating temperatureof said envelope under the exciting influence of electrons emanatingfrom said source when operated, and con-,

ductor means connected to said source and sealed through said envelope;said voltage convertingmeans being mounted within said lamp andelectrically connected to said coating and conductor means andelectrically oriented with respect thereto to effect full waverectification of alternating voltage applied to said source through saidconductor means and thereby maintain said coating positive in polaritywith respect to and at substantially the same potential as that appliedto said source.

5. The combination which comprises, means for converting alternatingvoltage to a unidirectional potential; and anincandescent-cathodoluminescent lamp comprising an incandescible sourceof radiant energy and electrons, a light-transmitting envelope enclosingsaid source, a light-transmitting electrically-conductive coating on theinner surface of said envelope comprising a cathodoluminescent phosphorhaving an efficient output in a predetermined region of the visiblespectrum at the normal operating temperature of said envelope under theexciting influence of electrons emanating from said source whenoperated, and conductor means connected to said source and sealedthrough said envelope; said voltage converting means comprisingrectifying elements mounted within said envelope at a location thereinremote from said source and connected to said coating and conductormeans, said rectifying elements being electrically oriented to effectfull wave rectification of alternating voltage applied to said sourcethrough said conductor means and to maintain said coating positive inpolarity with respect to and at a potential substantially equal to thatapplied to said source.

6. The combination which comprises, means for converting alternatingvoltage to a unidirectional potential; and anincandescent-cathodoluminescent lamp comprising an incandescible sourceof radiantenergy and electrons, a light-transmitting envelope enclosingsaid source, a light-transmitting electrically-conductive coating on theinner surface of said envelope comprising a cathodo-.

luminescent phosphor having 'an efiicient output in a predeterminedvregion of the visible spectrum at the normal operating temperature ofsaid envelope under the exciting influence of electrons emanating fromsaid source when operated, main conductor means connected to said sourceand sealed through 'an end of said envelope, and a hollow base membersecured to the said end of said envelope and electrically connected tosaid main.v

'to and at a potential substantially equal to that applied to saidsource.

References Cited in the file of this patent UNITED STATES PATENTS1,963,963 Barclay June 26, 1934 2,759,119 Thorington Aug. 14, 19562,763,814 Navarre Sept. 18, 1956 2,780,746 Arnott Feb. 5, 1957

